An extensive study was made of the origin of the Ge center in material which had been grown by means of organometallic vapor-phase epitaxy. By making a series of deductions, AsH3 was identified as being the source of Ge contamination. Depending upon the quality of the AsH3, a one to two orders of magnitude difference in the Ge trap density was observed. Long-term observations revealed the existence of a fairly constant Ge content throughout most of the AsH3 supply time. Various impurity getters were used in attempts to remove the Ge contaminant. It was found that, whereas most getters could eliminate O-related defects from AlGaAs, no getters were able to remove the Ge DX center.

W.Lee: Applied Physics Letters, 1996, 68[10], 1368-70